The present invention relates to a light detector, a radiation detector and a radiation tomography apparatus.
An X-ray detector wherein X-ray detection modules each formed with a plurality of photodiodes are provided side by side in plural form in a channel direction, has been used in a multi-slice type X-ray CT apparatus (refer to, for example, the following patent document 1).
FIG. 7 is a fragmentary plan view of a conventional X-ray detector. As shown in FIG. 7, a plurality of photodiodes 243 are disposed in matrix form in the X-ray detector, more specifically, one X-ray detection module of the X-ray detector. In the drawing, a z direction corresponds to a slice direction (body axial direction) and an x direction corresponds to a channel direction, respectively.
Since wirings (signal lines) 245 for fetching signal charges generated in the photodiodes 243 hardly pass light, they have heretofore been disposed in regions among the photodiodes 243 respectively.
Japanese Unexamined Patent Publication No. 2000-60840
However, the multi-slice type X-ray CT apparatus is accompanied by the problem that as the number of the photodiodes 243 in the slice direction (z direction) increases, the number of the wirings 245 that pass through the regions among the photodiodes arranged in the x direction increases, and there is hence a need to form fine wirings in the regions among the photodiodes 243, thereby causing a difficulty in its fabrication and a rise in its manufacturing cost.
Here, it is also considered that in view of a limit of wiring miniaturization or scale-down, as shown in FIG. 8, the interval d defined between adjacent photodiodes 243 arranged in an x direction is made wide and the width w of each photodiode 243 is made small. A problem, however, arises in that since the area of the photodiode 243 becomes small correspondingly, light detection efficiency is reduced.